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AB Purpose: Previous work identified an asymmetry in tissue desaturation changes in the left and right quadriceps muscles during on-ice skating at maximal speed in males. The effect of changing race distance on the magnitude of desaturation or leg asymmetry is unknown. Methods: Six elite male skaters (age = 23 +/- 1.8 yr, height = 1.8 +/- 0.1 m, mass = 80.1 +/- 5.7 kg, midthigh skinfold thickness = 7 +/- 2 mm) and four elite female skaters (age = 21 +/- 4 yr, height = 1.6 +/- 0.1 m, mass = 65.2 +/- 4.3 kg, midthigh skinfold thickness = 10 +/- 1 mm) were studied. Subjects completed time trials over three race distances. Blood lactate concentration and O2 uptake measurements were combined with near-infrared spectroscopy measures of muscle oxygenation (TSI) and blood volume (tHb) in the right and left vastus lateralis. Results: Neither race distance nor gender had a significant effect on the magnitude of maximal muscle desaturation ([DELTA]TSImax). Pattern of local changes in tHb during individual laps was dependent upon subtle differences in skating technique used for the different race distances. Linear regression analysis revealed asymmetry between the right and left leg desaturation in males during the final stages of each race distance, but not in females. At all race distances, local muscle desaturation reached maximal values much more quickly than global V[spacing dot above]O2peak. Conclusion: The use of wearable near-infrared spectroscopy devices enabled measurement of muscle oxygenation during competitive race simulation, thus providing unique insight into the effects of velocity and technique changes on local muscle oxygenation. This may have implications for training and race pacing in speed skating

The aim was to investigate the effects of a 48 h period of fluid, energy or combined fluid and energy restriction on salivary IgA (s-IgA) responses at rest and after exercise. Thirteen healthy males (age 21 (sem1) years) participated in four randomised 48 h trials. In the control trial participants received their estimated energy (12 154 (sem230) kJ/d) and water (3912 (sem140) ml/d) requirements. On fluid restriction (FR) participants received their energy requirements and 193 (sem19) ml water/d to drink and on energy restriction (ER) participants received their water requirements and 1214 (sem25) kJ/d. Fluid and energy restriction (F+ER) was a combination of FR and ER. After 48 h, participants performed a 30 min treadmill time trial (TT) followed by rehydration (0–2 h) and refeeding (2–6 h). Unstimulated saliva was collected at 0, 24 and 48 h, post-TT, and 2 and 6 h post-TT. Saliva flow rate (sflw) and s-IgA (ELISA) remained unchanged in control conditions and on ER. However, 48 h on FR decreased sflw (64 %) which most probably accounted for the increase in s-IgA concentration (P sem2); 24 h: 12 (sem2) μg/min;P

Firstly, to identify whether saliva flow rate, osmolality, and total protein are potential markers of hydration, we compared changes in these parameters with changes in plasma osmolality during progressive dehydration. Secondly, we compared the sensitivity of saliva parameters to track hydration changes with the sensitivity of urine osmolality. Thirdly, to test the hypothesis that dehydration, rather than neuroendocrine regulation, is responsible for the decrease in saliva flow rate during prolonged exercise, we compared flow rate and catecholamine responses to prolonged exercise with and without fluids.colon; Fifteen males (plasma osmolality 289 +/- 4 mOsmol x kg(-1); mean +/- SD) exercised (30 degrees C, 70% RH) with no fluid intake (NFI) until body mass loss (BML) of 1.1, 2.1, and 3.0% and on another occasion with fluid intake (FI) to offset losses.colon; Plasma and urine osmolality increased during NFI (plasma osmolality 3.0% BML: 298 +/- 4 mOsmol x kg(-1); P0.01). Saliva flow rate decreased (P0.01), saliva total protein increased (P0.01), and saliva osmolality increased from preexercise (50 +/- 11 mOsmol x kg(-1)) to 3.0% BML (105 +/- 41 mOsmol x kg(-1)) during NFI (P0.01). Saliva osmolality, urine osmolality, and saliva total protein correlated strongly with plasma osmolality during dehydration (r 0.87, 0.83, and 0.91, respectively; P0.01). During the FI trial, saliva flow rate and osmolality remained unchanged. Plasma catecholamine concentration increased during exercise (P0.01) with no difference between trials.colon; Saliva osmolality and total protein appear to be as sensitive as urine osmolality to track hydration changes during hypertonic-hypovolemia. These results also suggest that dehydration has a greater involvement in the decrease in saliva flow rate during prolonged exercise than neuroendocrine regulation.

PURPOSE: It has been suggested that, because of the low sitting position in short-track speed skating, muscle blood flow is restricted, leading to decreases in tissue oxygenation. Therefore, wearable wireless-enabled near-infrared spectroscopy (NIRS) technology was used to monitor changes in quadriceps muscle blood volume and oxygenation during a 500-m race simulation in short-track speed skaters. METHODS: Six elite skaters, all of Olympic standard (age = 23 ± 1.8 yr, height = 1.8 ± 0.1 m, mass = 80.1 ± 5.7 kg, midthigh skinfold thickness = 7 ± 2 mm), were studied. Subjects completed a 500-m race simulation time trial (TT). Whole-body oxygen consumption was simultaneously measured with muscle oxygenation in right and left vastus lateralis as measured by NIRS. RESULTS: Mean time for race completion was 44.8 ± 0.4 s. VO 2 peaked 20 s into the race. In contrast, muscle tissue oxygen saturation (TSI%) decreased and plateaued after 8 s. Linear regression analysis showed that right leg TSI% remained constant throughout the rest of the TT (slope value = 0.01), whereas left leg TSI% increased steadily (slope value = 0.16), leading to a significant asymmetry (P < 0.05) in the final lap. Total muscle blood volume decreased equally in both legs at the start of the simulation. However, during subsequent laps, there was a strong asymmetry during cornering; when skaters traveled solely on the right leg, there was a decrease in its muscle blood volume, whereas an increase was seen in the left leg. CONCLUSIONS: NIRS was shown to be a viable tool for wireless monitoring of muscle oxygenation. The asymmetry in muscle desaturation observed on the two legs in short-track speed skating has implications for training and performance. © 2012 by the American College of Sports Medicine.

The purpose of this study was to investigate the effects of prolonged exercise with and without a thermal clamp on neutrophil trafficking, bacterial-stimulated neutrophil degranulation, stress hormones, and cytokine responses. Thirteen healthy male volunteers (means ± SE: age 21 ± 1 yr; mass 74.9 ± 2.1 kg; maximal oxygen uptake 58 ± 1 ml·kg−1·min−1) completed four randomly assigned, 2-h water-immersion trials separated by 7 days. Trials were exercise-induced heating (EX-H: water temperature 36°C), exercise with a thermal clamp (EX-C: 24°C), passive heating (PA-H: 38.5°C), and control (CON: 35°C). EX-H and EX-C was comprised of 2 h of deep water running at 58% maximal oxygen uptake. Blood samples were collected at pre-, post-, and 1 h postimmersion. Core body temperature was unaltered on CON, clamped on EX-C (−0.02°C), and rose by 2.23°C and 2.31°C on EX-H and PA-H, respectively. Exercising with a thermal clamp did not blunt the neutrophilia postexercise (EX-C postexercise: 9.6 ± 1.1 and EX-H postexercise: 9.8 ± 1.0 × 109/liter). Neutrophil degranulation decreased ( P < 0.01) similarly immediately after PA-H (−21%), EX-C, and EX-H (−28%). EX-C blunted the circulating norepinephrine, cortisol, granulocyte-colony stimulating factor, and IL-6 response ( P < 0.01) but not the plasma epinephrine and serum growth hormone response. These results show a similar neutrophilia and decrease in neutrophil degranulation after prolonged exercise with and without a thermal clamp. As such, the rise in core body temperature does not appear to mediate neutrophil trafficking and degranulation responses to prolonged exercise. In addition, these results suggest a limited role for cortisol, granulocyte-colony stimulating factor, and IL-6 in the observed neutrophil responses to prolonged exercise.

The contribution of heat and exercise related stress to the release of heat shock protein 72 (HSP72) is currently unknown. The purpose of the present study was to determine the combined and independent effects of heat and exercise on the extracellular (e)HSP72 response. Eleven moderately trained male volunteers [means ± SD: age 21 ± 4 yr; body mass 75.7 ± 7.7 kg; maximal oxygen uptake (V̇o2 max) 57.8 ± 3.3 ml·kg−1·min−1] completed four 2-h, heat-manipulated, water-immersion trials. Trials were exercise-induced heat (EIH; rectal temperature change +2.2°C), clamped exercise (CEx; 0°C), passive heating (PHT; +2.3°C), and control (Con; 0°C). Exercise trials (EIH and CEx) comprised deep-water running at 58.5 ± 2.4 and 59.1 ± 1.7% v̇o2max. eHSP72 and catecholamine concentrations were determined by ELISA and HPLC, respectively, pre- and postimmersion. All trials induced an eHSP72 response ( P < 0.05) with postimmersion values significantly greater on EIH compared with other trials (6.0 ± 3.4; CEx 3.8 ± 2.6; PHT 2.7 ± 2.1; Con 2.2 ± 1.9 ng/ml). Exercising with a thermal clamp blunted the eHSP72 response, but postimmersion values were also greater than Con. PHT induced a large catecholamine response, but postimmersion eHSP72 values did not reach significance vs. Con. Given that exercising with a thermal clamp evoked a significant increase in plasma eHSP72 concentration, exercise-related stressors other than heat appeared influential in stimulating HSP72 release. Moreover, the catecholamine data from PHT suggest neither epinephrine nor norepinephrine was solely responsible for eHSP72 release.

To determine the effect of a 48-h period of either fluid restriction (FR), energy restriction (ER), or fluid and energy restriction (F + ER) on 30-min treadmill time trial (TT) performance in temperate conditions.Thirteen males participated in four randomized 48-h trials (mean +/- SD: age, 21 +/- 3 yr; VO2max 50.9 +/- 4.3 mL x kg(-1) x min(-1)). Control (CON) participants received their estimated energy (2903 +/- 199 kcal x d(-1)) and water (3912 +/- 500 mL x d(-1)) requirements. For FR, participants received their energy requirements and 193 +/- 50 mL x d(-1) water to drink, and for ER, participants received their water requirements and 290 +/- 20 kcal x d(-1). F + ER was a combination of FR and ER. After 48 h, participants performed a 30-min treadmill TT in temperate conditions (19.7 +/- 0.6 degrees C). A separate investigation (N = 10) showed the TT to be highly reproducible (CV 1.6%).Body mass loss (BML) was 0.6 +/- 0.4% (CON), 3.2 +/- 0.5% (FR), 3.4 +/- 0.3% (ER), and 3.6 +/- 0.3% (F + ER). Compared with CON (6295 +/- 513 m), less distance was completed on ER (10.3%) and F + ER (15.0%: P0.01). Although less distance was completed on FR (2.8%), this was not significantly different from CON.These results show a detrimental effect of a 48-h period of ER but no significant effect of FR on 30-min treadmill TT performance in temperate conditions. Therefore, these results do not support the popular contention that modest hypohydration (2-3% BML) significantly impairs endurance performance in temperate conditions.

The effects of the first 19 weeks of U.K. Parachute Regiment (PARA) training on upper respiratory tract infection (URTI) incidence and immune function (circulating leukocyte counts, lymphocyte subsets, lipopolysaccharide-stimulated neutrophil degranulation, and salivary immunoglobulin A concentrations) were investigated for 14 PARA recruits and 12 control subjects. No significant differences were reported between groups for the number or duration of URTIs, lymphocyte subsets, or salivary immunoglobulin A concentrations during training. URTI incidence was greater in the PARA group at weeks 2 and 3 (p < 0.05), coinciding with a decrease in circulating leukocyte and lymphocyte counts (p < 0.05). Neutrophil degranulation was similar in the PARA and control groups at weeks 0 and 19. Decreases in saliva flow rate occurred in the PARA group at week 15 and weeks 18 to 20 (p < 0.05). These results show a limited effect of PARA training on URTI incidence and immune function. The progressive decrease in saliva flow rate during PARA training may indicate an ensuing state of hypohydration.